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Threat Modeling for Software Developers: STRIDE-Light for Apps & Games

Threat modeling sounds intimidating, right? Like something only security gurus do. But for your app, game, or software under the Cyber Resilience Act (CRA), it's about systematically thinking about what could go wrong. Recital 54 implies this when it says manufacturers should identify relevant risks. A simplified approach like "STRIDE-Light" can be super effective.

What is STRIDE?​

STRIDE is a popular threat modeling mnemonic that stands for:

  • Spoofing: Pretending to be someone or something else.
  • Tampering: Modifying data or code.
  • Repudiation: Denying an action.
  • Information Disclosure: Exposing sensitive information.
  • Denial of Service: Making the system unavailable.
  • Elevation of Privilege: Gaining higher access rights.

STRIDE-Light for Your Software​

You don't need a PhD in STRIDE to use it. For your game or app:

  1. Break Down Your Product: Think about key features or components. User login? In-app store? Leaderboard service? Data sync?
  2. Apply STRIDE to Each Part:
    • Spoofing: Could someone fake a high score in your game? Impersonate another user in your app?
    • Tampering: Can a player modify their save game file to get unlimited currency? Can an attacker alter data your app sends to its backend? (Annex I, Part I, (f) requires protecting integrity)
    • Information Disclosure: Does your app accidentally log sensitive API keys? Can someone intercept traffic to see other users' data? (Annex I, Part I, (e) requires protecting confidentiality)
    • Denial of Service: Could a flood of bad requests crash your game's login server? (Annex I, Part I, (h) requires protecting availability)
    • Elevation of Privilege: If your app has admin functions, can a regular user somehow access them?

Don't aim for an exhaustive list for every tiny function. Focus on the most critical parts and the most plausible threats for your specific product.

Key Takeway​

Threat modeling, even a simplified STRIDE-light version, helps you proactively identify potential security weaknesses in your software. It's a practical way to meet the CRA's expectation of identifying relevant risks.